You're correct it.
It started happening on my PC with version 1.4.X of Gnucleus.
VERY tiresome to say the least.

Usually this happens when I get a blue screen error message from Win98SE where the message says I perhaps can continue using my PC as usual after the error message. BUT I can't use it since my PC loses connection with internet even though I am still connected to my ISP. Restart seems to be the only salvation.